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Showing 1 to 13 of 13 for “"Acoustic analogy"”.
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Development & Validation of the Acoustic Analogy Code for Jet Noise Predictions
… sound source is developed based on Lighthill's acoustic analogy theory. The acoustic analogy equation allows calculating the sound intensity in terms of the integral over the volume with distributed Lighthill tensor of unsteady flow fluctuations. A FORTRAN code is written to perform the …
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A statistical jet-noise model based on the acoustic analogy and a RANS solution
… and low-frequency approximations of the Lilley analogy Green's function. The high-frequency approximation is determined by combining a moving-medium Lighthill analogy and ray acoustics. The low-frequency model is made by using a flow-factor approach on each component of the source two-point …
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The Computation of Exact Green's Functions in Acoustic Analogy By a Spectral Collocation Boundary Element Method
… exact, or tailored, Green's functions for use in acoustic analogy. The effects of sound propagation and scattering by solid surfaces are included in the exact Green's function, which is tailored for a specific geometry. The exact Green's function is computed using a spectral collocation boundary …
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Computation and control of flow-induced noise behind a circular cylinder using an acoustic analogy approach
The computational aeroacoustics (CAA) research, which focuses on predicting acoustics by means of advanced numerical techniques, has recently gained a great deal of progress. In most applications, the prediction of both the sound source and its far-field propagation is necessary as required by …
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The Analysis and Prediction of Jet Flow and Jet Noise about Airframe Surfaces
… surfaces exhibit a complex behavior in which acoustic and aerodynamic characteristics are altered. The physical understanding and accurate modeling of these characteristics are essential to designing future low-noise aircraft. In this thesis, an alternative approach is created for predicting …
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Physics-based aeroacoustic modelling of bluff-bodies
… noise source characteristics and the resulting acoustic far-field. Three-dimensional compressible Navier-Stokes simulations were performed to solve the unsteady turbulent near-field flow and the acoustic analogy was used to predict the resulting far-field acoustic pressure. The flow solver …
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Slat aerodynamics and aeroacoustics with flow control
… study primarily investigated the flow and aeroacoustics associated with the slat of a three-element aerofoil in approach conditions. The study assessed importance of several factors and examined their aerodynamic impacts. The factors investigated were aerofoil incidence, slat angle, slat cusp …
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Installed jet noise
… the first of which is based on the Lighthill's acoustic analogy theory. The second part embraces Amiet's approach to model the sound due to the scattering of jet instability waves. It is shown that the significant low-frequency noise enhancement observed in installed jet experiments is due to …
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Bio-Inspired Axial Fan Design, 3D Printing Fabrication and Characterization for Noise and Flow Performance Optimization
… requirements, and stringent environmental acoustic regulations. In this context, axial-flow fans represent a key technological component, acting as major sources of both tonal and broadband aerodynamic noise, with direct implications for public health, building energy performance, and urban …
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Anwendung des Lattice-Boltzmann-Verfahrens zur Berechnung strömungsakustischer Probleme
… to application to numerical solution of flow acoustic problems. In the first part of this study the description of sound wave propagation by common variants of the Lattice-Boltzmann-model is examined by calculation of phase velocity and effective viscosity for sound waves. Schemes with nine …
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Propeller Noise Prediction of an Urban Air Mobility Vehicle in Urban Environment
… with the Ffowcs–Williams and Hawkings (FW–H) acoustic analogy to capture both unsteady flow dynamics and far-field sound radiation.</p> <p>The first part focuses on the investigation to transition (tilt) flight conditions, where both blade–vortex interaction (BVI) and blade–wake interaction …
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High Fidelity Open Rotor Noise Prediction
… to be the most realistic description of aeroacoustic noise generation, as it is a direct rearrangement of the Navier-Stokes equations. The \fwh\ equation is difficult to solve for realistic test cases such as an open rotor, and is susceptible to several types of error. This thesis categorises …
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Aeroacoustics Applications to Jets and Rotors
<p>Aeroacoustics plays a critical role in the advancement of propulsion technologies for both conventional and emerging aerial systems. This dissertation investigates two key topics: noise suppression in supersonic rectangular jets and rotor noise characterization in hover and ground effect. Using …